The Earth's atmosphere blocks IR emissions coming from the Earth, which is the cause of a greenhouse effect and of a moderate temperature, favourable to life. In the atmosphere, it is mainly carbon dioxide CO2 that is responsible for this natural greenhouse effect. The emission, by man, of certain gases (including CO2 from fossil fuels) amplifies this effect, causing global warming with its consequences on the climate: storms, floods, variation of pack ice surface area and glacier recession.
The Kyoto protocol (1997) aims to reduce the emission of 6 greenhouse gases (CO2, CH4, N2O, HFC, PFC, SF6) in the commitment period 2008-2012, by 5% globally relative to 1990 (reference year).
The greenhouse effect of a given product is quantified by its GWP (Global Warming Potential) which takes into account the intrinsic effect of radiation absorption by the molecule but also the lifetime of the molecule in the atmosphere (or what amounts to the same thing as its concentration during a given period of time, usually 1 century). This GWP is given relative to CO2, taken as a reference gas.
Fluorinated solvents have been used for a long time in high-technology industries such as electronics, aeronautics, precision mechanics or the medical sector. In these fields, the objective always remains the same, namely to obtain a surface of very high cleanliness, which is a question of removing greasy soiling which is more or less polar, solid particles, electron flow or water.
In precision cleaning there is often the presence of very complex parts equipped with grooves, ribs or blind holes that the solvent will imperatively have to wet in order to be effective in these difficult places. Fluorinated solvents are from the family of solvents that provide the best possible wetting of a surface, which is expressed by very low surface tensions (18.4 mN/m for HCFC 141b and 13.3 mN/m for HFC 365 mfc versus 32.3 mN/m for perchloroethylene, another non-fluorinated cleaning solvent, for example). Another advantage of a high wetting is obtaining faster drying of substrates.
At practically identical molecular weights, fluorinated solvents have lower boiling points and higher vapour pressures. Thus, HCFC 141b boils at 32° C. whereas chloroform boils at 61° C. These two properties (low boiling point and high vapour pressure) are favourable to the use of these solvents in conventional industrial machines that operate with a vapour phase enabling the rinsing and drying of parts and also the regeneration of the solvent which is continuously distilled. The operating process of these machines, equipped with a heavy-duty system for cooling, by condensation, of the vapours on a coil, minimizes the drawback of the high vapour pressures used. Industrialists desire substitution solutions which can operate in their existing stock of machines.
Furthermore, hydrofluorocarbons are widely used in refrigeration and in heat transfer processes.